Downscaling Future Temperature and Precipitation Values in Kombolcha Town, South Wollo in Ethiopia
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Research Article Volume 5:4, 2021 Journal of Environmental Hazards ISSN: 2684-4923 Open Access Downscaling Future Temperature and Precipitation Values in Kombolcha Town, South Wollo in Ethiopia Kasye Shitu1* and Mengesha Tesfaw2 1Department of Soil Resource and Watershed Management, Assosa University, Assosa, Ethiopia 2Departments of Soil Resource and Watershed Management, Wolidia University, Wolidia, Ethiopia Abstract Whilst climate change is already manifesting in Ethiopia through changes in temperature and rainfall, its magnitude is poorly studied at regional levels. Therefore, the main aim of this study was statistically downscale of future daily maximum temperature, daily minimum temperature, and precipitation value in Kombolcha Town, South Wollo, in Ethiopia. For this the long term historical climatic data were collected from Ethiopian National Meteorological Agency for Kombolcha station and the GCM data were downloaded from the global circulation models of, the Canadian Second Generation Earth System Model from the link (http://climate scenarios.canada.ca/?page=dstsdi). For future climate data generation among the different downscaling techniques, the statistical down scaling method, a type of regression model was used and the variations of temperature (maximum and minimum) and precipitation in the town for annually and seasonally condition were analysis based on the base of the 2020s, 2050s and 2080s. In the future, relative to the observed mean value of annual rainfall in Kombolcha town, mean value of annual rainfall will decrease 1.36% - 7.03% for RCP4.5and 5.37% -13.8% for RCP8.5 emission scenarios in the last 21 century. Both maximum and minimum temperature of the town will be increased in the future time interval for both RCP4.5 and RCP8.5 emission scenarios. The rise in temperature will exacerbate the town maximum heat effects in warm seasons and decrease in precipitation is expected along with a possible risk of water supply scarcity due to a low level of water supply access and a high rate of urbanization. Keywords: Downscaling • Kombolcha • Precipitation and temperature • Emission scenarios. Introduction significantly increasing trends in the frequency of hot days, are much larger increasing trends in the frequency of hot nights. The average number of ‘hot’ days per year increased by 73 (an additional 20% of days) between 1960 Global climate has changed over the last century mainly, due to and 2003 [12]. In the country related with precipitation, consistent models’ anthropogenic factors [1]. Climate change is described as the most universal ensemble of different model, indicating increases in total precipitation occurring and irreversible environmental problem facing the planet Earth [2] and in ‘heavy’ events, and increases in the magnitude of one-day maxima and five- becoming one of the most threatening issues for the world today in terms of its day maxima rainfall [13]. global context and its response to environmental and socioeconomic drivers [3]. The Intergovernmental Panel on Climate Change (IPCC) in its Fourth Whilst climate change is already manifesting in Ethiopia through changes Assessment Report observed an increase of 0.74 ± 0.18°C in mean annual in temperature and rainfall, its magnitude is poorly studied at regional levels global temperature [1]. According to [4] most scholars have agreed that the [2]. This is because of that, the results of the temperature and precipitation global annual average temperature is likely to be 2°C above pre-industrial data that obtained from meteorological observation of some regions are levels by 2050. This may makes the world more intense rainfall, frequent and missing and limits the downscaling of future weather values from general intense droughts, floods, heat waves, and other extreme weather events. circulation models. Now a time we can determine the consequences of climate Africa is considered as the most vulnerable continent to climate change in change earlier and our self for necessary adaptation measures by simulate the world [5]. According to AR4, it is very likely that all of Africa will warm up changes in climatic elements of the present and future from global general during this century and that, throughout Africa and in all seasons, the warming circulation models (GCMs) [12]. However, due to, coarse resolution of the will be larger than the global annual mean warming [6]. According to future GCM output it is difficult to apply the raw data of GCMs at a local scale, such as projections, precipitation and temperature will increase over Eastern Africa in the watershed scale or points of emphasis of this study urban climate change the coming century [7]. It is predicted that the temperature in Africa continent without downscaling [14]. Therefore, in order to use the results of general will rise by 2 to 6°C over the next 100 years [8]. circulation model to study the impact of climate change on a local scale, it is common to downscale and bring the results into the finest resolution. This can Regionally, in East Africa, studies indicate that in countries like Burundi, be done through the development of tools for downscaling GCM predictions of Kenya, Sudan, and Tanzania people are badly hit by the impacts of climate climate change to regional and local or station scales [15]. chang [9,10]. Temperature projections in the region indicates that, the median near-surface temperature in the 2080 to 2099 period will increase by 3°C to The Statistical Downscaling Model (SDSM) is a freely available tool that 4°C when it compared to the 1980 to 1999 period. It has to be underlined produces high resolution climate change scenarios result from GCMS for local that this increase is about 1.5 times the projected global mean response [6]. scale climate change study [16]. The SDSM provides reasonably good results Because of significant dependence on the agricultural sector for production, after calibration with NCEP predictor variables [1] and establish a relationship employment, and export revenues, Ethiopia is seriously threatened by climate between past local climate and past GCM outputs and extend this relationship change, which contributes to frequent drought, flooding, and rising average into the future, to generate future local climate series from future GCM output temperatures [11]. In the country, the daily temperature observations show [17]. The projection of future climate value is critical information that is needed to assess the impact of potential climate change on human beings and on the *Address for Correspondence: Kasye Shitu, Department of Soil Resource and natural environment [18]. It is also helpful for long-term planning development Watershed Management, Assosa University, Assosa, Ethiopia; Tel: 910134821; at both regional and national levels for mitigation and adaptation strategies of E-mail: [email protected] future climate change as, it gives opens space for a set of potential responses [19]. Copyright: © 2021 Kasye Shitu, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits In Ethiopia, studies like, statistical downscaling for daily temperature and unrestricted use, distribution, and reproduction in any medium, provided the rainfall in South Wollo [20], the study of future changes in climate parameters in original author and source are credited. Amhara Regional State [2], future climate studies in northwestern Ethiopia for Received 11 May 2021; Accepted 29 June 2021; Published 07 July 2021 assessing the hydrological response of the Gilgel Abay River to climate change Shitu K, et al. J Environ Hazard, Volume, Volume 5:4, 2021 in the Lake Tana Basin [12], climate change impact on the Geba Catchment Materials and Methods in Northern Ethiopia [21], GIS based quantification and mapping of climate change vulnerability hotspots in Addis Ababa [14], Impacts of Climate Change Description of the study area Under CMIP5 RCP Scenarios on the Hydrology of Lake Ziway Catchment [22], Impact of Climate Change on Hydrology of the Upper Awash River Basin [23], The study was conducted in Kombolcha town, which is found to the North Impact of Climate Change on Evapotranspiration and Runoff in Awash basin East of Ethiopia in Amhara regional state of South Wollo Zone. The town is [24] and Climate Change Impact on Water Resources in the Awash Basin [25] located in a range of altitudes and longitude between11º1'30"- 11º15'0" N were conducted by using downscaling applications in different time intervals latitude and 39º40'30" - 39 º 49’30” E longitudes. It is one of the industrial throughout all direction of the country to detect climate change impacts in towns in Amhara regional state of Ethiopia. Based on the 2007 national agricultural and hydrological applications. But, applications of statistical census conducted by the central statistical agency of Ethiopia (CSA), downscaling of general circulation models for future time temperature and Kombolcha has a total population of 85,367 of whom 41,968 are men and precipitation value estimation for industrial town of Kombolicha, South Wollo in 43,399 women; 58,667 or 68.72% are urban inhabitants living in town of Ethiopia has not been undertaken. Kombolcha, the rest of the population is living at rural Kebles around the town (Figure 1). It is important to some large cities of East and North African [26,27] and Addis Ababa city in Ethiopia [14,18] use of downscaled results from GCMs to The town is a plain land with altitudes difference of 1,500 m - 1,840 m assess future projections and to identify adaptation measures were explored above sea level and surrounded by hills. It is crossed by Borkena River and recently. Only a few studies are available for Kombolcha town, which differ numerous small streams. The Borkena valley and the gullies formed by the in method and temporal scale from these studies [28] and [29]. So, in order streams from the surrounding hills have made the configuration of the town to fill the above listed limitation by establish a relationship between past undulating.